Non-contact temperature measurement is required for many objects. Thermopile detectors are one example of detectors that can be useful to make non-contact temperature measurements. When using thermopile detectors, it is desirable to have as large a signal as possible from the target object to distinguish the signal from noise and background sources. Emissivity, which varies from material to material and from surface to surface, and which can vary with surface temperature and other surface conditions such as oxidation, affects the signal level of a thermal detector.